Leary has already finished filming the final season of the FX drama, which will air next year.

"There's a final twist right before the final credits," he told the Boston Herald. "Hopefully the audience will like it."

He refused to reveal too many details about the storyline but his co-star Lenny Clarke claimed that the final scene is "insane".

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"It's not going to leave you like The Sopranos," Clarke added. "I thought that ending sucked. I thought my TV broke... [Rescue Me's ending] is pretty amazing. I think people are going to be really happy with it."